In-situ blade sharpener

ABSTRACT

A blade sharpening device easily connectable to a source of rotating power, such as a battery powered hand drill, and having a housing, a selectably locatable pitch adjuster and a clamping mechanism means for maintaining the housing and grinding surfaces of the sharpening device at a desired grinding angle. The housing extends completely over the width of the rotatable drums wrapped with grinding surface. By clamping the device directly to the blade and stabilizing the device in this position, the operator has greater control and stability of the sharpener when in use on, for example, a lawn mower blade which is still attached to the lawn mower drive shaft at the underside of the lawn mower housing. This on-site, in-place blade sharpening capability eliminates the necessity of removing the blade for its sharpening, while still allowing easy and safe sharpening of the blade.

CROSS REFERNCE TO RELATED APPLICATION

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

The present invention is directed to blade sharpening devices in generaland more particularly to blade sharpening devices suitable for on-site,in-place use on blades which are, for example, attached to a drivingmember, such as, for example, a lawn mower blade, and even moreparticularly to such a device which has a safety guard and associatedmeans for allowing the operator to manually control the positioning andmovement of the sharpening device. In additional to the preferred,exemplary application of lawn mower blades, the device can be used tosharpen other devices, such as, for further example, garden tillers,shovels, hoes, as well as scythes, cane knives, sweepers, bladed “weedeaters”, bush hogs, etc.

It is often the case with a mechanically powered blade, such as theblade of a conventional rotary mower, that from time-to-time the edge ofthe blade will require sharpening. The sharpening of the blade edgeincreases the cutting efficiency of the blade by allowing the edge ofthe blade to cut the item intended instead of tearing the item as ablunt edge will do.

One problem with maintaining a sharp edge on such a blade is theinconvenience involved in removing the blade from its driving member inorder to sharpen the blade on a blade sharpening device, such as, forexample, a bench mounted grinding wheel. It would be better, therefore,to have a blade sharpening device which is portable and capable of useon the blade in-place, while the blade remains attached to its drivingmember.

There are many portable devices known. However there remains problemswith such devices due to, inter alia, problems of safety, the ability tomonitor the edge sharpening while it is in progress, and accuracy incontrolling the angle of the edge being ground since the operator isrequired to manually hold the device against the blade.

U.S. Pat. No. 2,921,416 to Shanahan discloses a “lawn mower sharpener”in which a power drill is held up-side-down in a cradle-type holderdriving a grinding wheel 23, in which the holder includes positioningextensions or protuberances which directly contact the lawn mower bladeand bed plate, respectively, causing the device to be directly carriedby the blade and its associated structure. Such a device is very limitedin its application being confined to use basically only with the lawnmower design illustrated and can be relatively dangerous to use, withthe rotating grinder being exposed to the operator during use.

U.S. Pat. No. 2,993,312 to Holland et al discloses a blade sharpeningdevice, which is completely hand manipulated. The sharpener is poweredby a portable power tool, and has a wheel type grinding stone rigidlysecured to a shaft and a frustro-conically shaped guide which isrotatably mounted on the shaft adjacent to the grinding stone. The shaftis connectable to the chuck of a portable power tool. The wheel and thefrustro-conically shaped guide are arranged on the shaft with thesmaller end of the guide adjacent to the wheel type stone to present afixed angular grinding surface to a blade held against the guide. Thedevice includes no guard for the rotating sharpening members, making itrelatively dangerous, and no means are provided to allow the operator tograsp the device at both ends, making it more difficult to use andaccurately position.

U.S. Pat. No. 3,019,568 issued Feb. 6, 1962 to Sauers et al discloses alawn mower grinder and sharpener for a reel type lawn mower in which thesharpener is braced (17/18) on one of the lawn mower's basic structuralcomponents, i.e. the spacer rod 15. As above, this approach of directbracing on the lawn mower structure greatly limits the applicability anduse of the device. Also, as above, the substantial exposure of therotating sharpening device to the operator makes the device relativelydangerous to use.

U.S. Pat. No. 3,122,865 issued Mar. 3, 1964, to Kolling discloses apower tool attachment for the sharpening of rotary mower blades. Theattachment includes a guide that is spaced from the grinding surface andmeans for adjusting the spacing between the guide and the grindingsurface by disassembling the sharpening device and removing a spacingelement, thereby, allowing the use of an unused portion of the grindingsurface when a portion of the grinding surface becomes worn. LikeHolland et al, the Kolling device includes no guard for the rotatingsharpening member, making it relatively dangerous to use, and no meansare provided to allow the operator to grasp the device at both ends,making it more difficult to use and accurately position.

U.S. Pat. No. 3,238,673 issued Mar. 8, 1966, to W. F. Thompson disclosesa non-portable, blade sharpener having a rotary guide for maintainingthe angle of the blade in relation to a rotating, flat, grindingsurface, wherein the guide includes protrusions which cause the blade tomove radially, in an upward and downward direction, against the rotatinggrinding surface. This patent is not directly relevant to the field ofthe invention and does not help to overcome the deficiencies of theprior art discussed above and below.

U.S. Pat. No. 3,648,414 issued Mar. 14, 1972 also to W. F. Thompsondiscloses a scissor-type blade sharpener and likewise is not directlyrelevant to the field of the invention and does not help to overcome thedeficiencies of the prior art discussed above and below.

U.S. Pat. No. 3,800,480 issued Apr. 2, 1974, to Keating discloses aportable, on-site, in-place blade sharpener which includes an angulardrive means mounted in a housing containing an enclosed, dedicated,electric motor, with the device being hand-manipulated by the operatorgrasping the motor housing 14 by itself or in conjunction with thesharpener housing 19 and moving the device along the blade edge. Theangular drive means is connected between the electric motor 21 and agrinding wheel 35 for coupling the rotational energy of the internalmotor to the grinding wheel. Such an approach, in which the device ridesthrough a guide plate 11 in flat-face-to-flat-face surface engagementwith the underside of the blade and which does not use a multi-purposeelectric drill but rather a contained, dedicated motor, is relativelyinflexible in its use and relatively expensive. It does not providefreedom of lateral or angular movement, nor the easily controllable andstrongly grippable handle of a power drill, all of which can assist inthe easy and accurate positioning of the rotating sharpening member onthe blade.

U.S. Pat. No. 5,371,977 issued on Dec. 13, 1994 to Liner discloses anon-site, in-place, portable blade sharpening device for lawn mowerblades and the like using the standard type portable electric hand drillfor power which device is hand-manipulated, adaptable for use with manydifferent lawn mower designs, relatively safe in use, and easily, stablyand accurately moved and positioned by the operator using an easilymaneuverable two-hand grasp at opposed ends of the combined device anddrill.

U.S. Pat. No. 6,666,758 issued on 23 Dec. 2003 to Parrott discloses ageneral a lawn mower blade sharpening device and a method of sharpeninglawn mower blades using the device. The device comprises a motor toproduce rotational movement of a flexible drive cable, where a two-sidedgrinding disk is attached to the drive cable such that operation of themotor rotates the grinding disk at a relatively high speed. The grindingdisk is composed of a material suitable for removing metal from the dullmower blade in order to create a sharp edge. Preferably, a universaljoint is provided between the flexible cable and the grinder body orgrip to provide for maximum maneuverability of the grinding disk. Themotor is preferably battery operated, but may also be electrically orgasoline operated. With this device, the lawn mower blade can besharpened without the need to remove the blades from the mower, as thecombination of flexible drive cable and two sided grinding wheel enablethe operator to abrade both sides of the cutting blade to create a sharpedge.

The above mentioned inventions can be unsafe since the sharpeningmechanisms are exposed and the operators hands are in close proximity tothe blade as well as the sharpening surfaces that abrade the edge of theblade. Furthermore, the manual process of holding the sharpening devicesagainst the blade does not allow for uniform sharpening and may resultin “kick-back” of the devices if a nick or dent is hit with thesharpening device. Optimally, a need exists for a device that ispotable, can be directly clamped to the blade that needs sharpeningin-situ, and needs minimal manual manipulation.

BRIEF SUMMARY OF THE INVENTION

It is thus an object of the present invention to provide a portableblade sharpening device for lawn mowers and the like which has a housingwhich will contain the rotating sharpening segment protecting theoperator from projectiles created during the sharpening process and thegrinding surface as it moves along the blade. The housing also providesa gripping surface for the operator to hold the sharpening device inposition while clamping the device to the blade enabling the operator tohave free hands once the device is in the clamped position while theblade is still in place in its working position on the lawn mower orlike machine. The grinding surface shall be slidably mounted to anextension rod allowing for the sharpening segment to move along theentire length of the area of the blade that is to be sharpened withouthave to loosen the clamps or remove the entire housing from the blade.

It is another object of the present invention to provide a bladesharpening device which will increase the operator's control of andaccuracy in the positioning of the grinding surface of the sharpeningdevice on the blade during the sharpening process and does not requireit to be braced against any part of the housing of the lawn mower orother such structural parts or machinery except for the blade itself sothis device could be used on various sizes, models, and configurationsof lawnmowers or other devices that utilize a blade. The presentinvention provides a method of sharpening an edge of the blade of a lawnmower while it is still attached to a drive member. This enables theoperator to save time and energy by not having to remove the blade andplace it in a separate detached clamp or vice.

Accordingly, the present invention in its preferred embodiment isdirected to a blade sharpening device including a housing preferablywith top, side, and bottom surfaces which extend over the complete axialwidth and cover over all of the rotating sharpening segment. The housingnot only protects the operator from flying debris or fragments but alsoprovides a safe area for the operator to grasp in several different waysin manipulating the device to secure it to the lawn mower blade.Additionally, a selectively located drive shaft, clamp tightening leverand sharpening segment pitch adjuster, each having a multiplicity ofpossible positions or locations preferably is also included, furtheradding to the ease of control and positioning of the device.

The blade sharpening segment within the housing comprises a rotatablegrinding member composed of two rotatable drums with a grinding surfacesuch as emery paper securely wrapped around the two rotating drums. Oneof the drums is connected to a shaft member with a shank for connectionto, for example, a portable hand drill for the driving of the grindingmember. The shaft member, which is secured to one of the drums has anend thereof adapted for connection with a source of rotational power,such as, for example, a battery or AC powered, electrical drill, isfurther associated with securing means for securing the drum thereinadapted to allow the grinding surface to be drivingly rotated about thelongitudinal axis of the drum.

In use, the operator inserts the edge of the blade that needs to besharpened through a receiving means in the housing and secures the clamponto the blade which causes the whole sharpening device to be affixedsecurely to the lawn mower blade still attached to the body of themower. The operator can adjust the angle of the grinding surface withthe pitch adjuster. The operator then uses the drill to rotate the drumto which the drill is attached which causes the grinding surface torotate freely within the housing of the sharpening device. The operatorcan re-position the pitch and the blade that is clamped within thehousing to maximize the sharpening capability. The use can also manualslide the grinding member along the shaft and across the blade, or athreaded screw-shank mechanism can mechanically cause this action tooccur.

The present invention thus provides an on-site, in-place, portable bladesharpening device for lawn mower blades and the like, preferably usingthe standard type portable electric hand drill for power, which deviceis hand-manipulated, adaptable for use with many different lawn mowerdesigns, as well as many other devices, relatively safe in use, andeasily, stably and accurately aligned and positioned by the operatorusing an easily maneuverable clamping device and pitch adjuster thatallows the operator to only hold the apparatus that is attached to theshank member to cause the rotation of the drum. This allows the operatorto have free use of his other hand during the sharpening process. Inaddition to the particular application of lawn mower blades, the deviceof the invention can be used to sharpen other devices that have a bladethat has a surface large enough to be clamped and have a rotatinggrinding surface applied to the edge of the blade, such as, for furtherexample, garden tillers, shovels, hoes, as well as scythes, cane knives,sweepers, bladed “weed eaters”, bush hogs, etc

BRIEF DESCRIPTION OF DRAWINGS

For a further understanding of the nature and objects of the presentinvention, reference should be had to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like elements are given the same or analogous reference numbersand wherein:

FIG. 1 is a front view of a preferred embodiment of the invention withthe position of the pitch adjusting member and the shaft connected tothe rotatable grinding member and the clamping mechanism;

FIG. 2 is across sectional view from the end opposite the shaft memberadapted for connection with a source of rotational power and a bladeinserted into the longitudinal aperture;

FIG. 2A is an exploded side view of the device showing a preferred pitchadjuster location and predetermined angle formation slots; and

FIG. 3 is a front perspective view of the preferred grinding memberillustrated in use with dual drums wrapped in the grinding surface andthe position of the pitch adjuster.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the preferred, exemplary embodiment of the blade sharpeningdevice 8 of the invention with the main elements of the device includinga grinding member 10; a shaft member 12; a housing member 14, which canbe transparent if so desired, having an upper plate 71 and a lower plate72; and a clamping mechanism 16 having a clamping end 27 mounted to anupper plate 71 which is movable in a vertical direction by the clampingmechanism 16. The entire invention can be constructed of any suitablematerial that has the strength and durability. The preferred material isa composite of man-made organic para-aramid fibers.

The shaft 12 may be constructed of any material which has sufficienttorsional strength to rotate and carry the grinding member 10. Suitableshaft constructing materials include metals, such as steel, fiberglass,and plastics having the required torsional strength. In the preferredembodiment shaft member 12 is constructed of a man-made organicpara-aramid fiber. The shaft member 12 includes an external shaft end orshank 24, which is adapted for connection with a source of rotationalpower, such as, for example, a battery or AC powered hand drill 66. Theinvention contemplates all methods, well known in the art, of connectinga shaft to a source of rotational power. The grinding member 10 rotatesfreely around an imaginary axis 80 located in a longitudinal aperture81. The grinding member 10 can slide freely in a horizontal directionalong the shaft 12. The shaft 12 may be threaded so when a rotationalforce is applied, the grinding member 10 mechanically moves horizontallyalong the shaft 12. Also, it is contemplated that a directionalhorizontal force applied by the operator on the pitch adjuster 20 shallcause the grinding member 10 to move horizontally along the shaft 12.

The housing 14 can be pre-cast or formed in a C-channel form with afirst end plate 42 and a second end plate 43. The present invention 8contemplates the fullest extent of coverage of the grinding member 10 bythe housing 14, with additional horizontal space to allow for thegrinding member 10 to slide along shaft 12 for the length of the blade62 to be sharpened while still maintaining the blade sharpeningcapability of the grinding member 10. The longitudinal aperture 81formed by the C-channel housing 14 allows for a blade 62 to be insertedthrough the longitudinal aperture 81 into the housing 14 and come torest against the grinding member 10 through which imaginary axis 80runs.

FIG. 2 shows an axial view opposite from the shaft end 24. Also shown,is a preferred, threaded method of attaching the clamping mechanism 16to the housing 14 and the pitch adjuster 20. Although any known methodof rigidly, mounting a clamp to a surface is contemplated by the presentinvention, in this preferred embodiment, clamping end 27 of clampingmechanism 16 is threaded and first end plate 42 of housing 14 includescompanionately threaded, alternate bores 48 and 49. Likewise, it iscontemplated in this invention that the clamping end may be located onsecond end plate 43. Similarly, any known method of rigidly, mounting apitch adjuster 20 to a surface is contemplated by the present invention,in this preferred embodiment, pitch adjuster 20 is rotatably affixed,such as by a ball-and-socket means to grinding member 10. Pitch adjuster20 penetrates first end plate 42 and can be secured in any individualslot of a series predetermined slots 45 which determines the angle 46that is formed between the blade 62 and the grinding member 10.Likewise, it is contemplated in this invention that the pitch adjuster20 may be located on second end plate 43. FIG. 2A is an exploded view ofthe first end plate 42 which may also depict second end plate 43.

In the preferred, exemplary embodiment grinding member 10 is constructedof two, opposed, co-operating drums 50 & 58. First drum 50 includes ashaft 24 and second drum includes an attachment for the pitch adjuster20. Grinding surface 25, such as emery paper, is wrapped around firstdrum 50 and second drum 58 to form a circular band 52 so as to allow itsfree rotation initiated by the application of the drive member 66attached to the drum 50. Frictional forces cause the underside ofgrinding surface 25 to remain frictionally affixed to the first drum 50and the second drum 58 while rotating along with the rotation of firstdrum 50. Frictional forces also cause the grinding surface 25 to causesecond drum 58 to rotate. Pitch adjuster 20 is in a fixed positionattached second drum 58 by a ball-and-socket, or similar means ofconnection.

FIG. 3 illustrates the blade sharpening device 8 of the invention in useon the blade 62 of a conventional rotary lawn mower. It shows the bladesharpening device 8 connected to a source of rotational power, in thiscase a conventional portable drill 66. The sharpening device 8 iscontrolled by the operator by housing 14 with the operator securing theclamping mechanism 16 to the blade 62 by using a threaded tighteningmechanism at clamping end 27. The clamping end is turned by the operatorwhich lowers the causes an arm 73 to move in the vertical direction,raising or lowering the upper plate 71, which is movably attached to thehousing 14 onto the blade 62 and securing the blade 62 between the upperplate 71 and the lower plate 72 of the housing 14. Next, the operatorpositions the pitch adjuster 20 against the edge of the blade 62 thatneeds sharpening. When the device 8 is properly positioned and angled onthe blade, the operator can attach to source of rotational power 66 tothe shaft mechanism 12. This arrangement gives the operator bettercontrol over the position of housing 14 on blade 62 by providing dualcontrol locations and does not require the sharpening device be bracedor supported on the machinery or housing which carries the blade 62, butis supported by the blade 62 itself

The operational position of housing 14 is also illustrated. Therelatively complete and full coverage of grinding member 10 by housing14 affords the operator protection from flying debris created during thesharpening process and also provides a handy surface upon which thelower part of the hand and the side of the little finger can be rested.

In additional to the preferred, exemplary application of lawn mowerblades, the device can be used to sharpen other devices, such as, forfurther example, garden tillers, shovels, hoes, as well as scythes, caneknives, sweepers, bladed “weed eaters”, bushhogs, etc.

It is noted that the embodiment described herein in detail for exemplarypurposes is of course subject to many different variations in structure,design, application and methodology. Because many varying and differentembodiments may be made within the scope of the inventive concept(s)herein taught, and because many modifications may be made in theembodiment herein detailed in accordance with the descriptiverequirements of the law, it is to be understood that the details hereinare to be interpreted as illustrative and not in a limiting sense.

1. A blade sharpening device, comprising: a grinding member having arotatable grinding surface adapted to grind an edge of desireddimensions on a blade; a shaft member, secured to said grinding member,having an end thereof adapted for connection with a source of rotationalpower; securing means for securing said grinding member to said shaftmember; a housing defining a receiving means comprising an upper plateand a lower plate between which said blade may be inserted and agrinding member cavity therein adapted to allow said grinding member torotate about an axis of a longitudinal aperture, when said grindingmember is secured by said securing means to said shaft member in amanner such that said grinding member is surrounded by said housing; aclamping mechanism, attached to said housing, having a means foradjusting said upper plate to compress said blade against said lowerplate to immobilize said blade during an application of said rotatinggrinding surface against said edge of said blade.
 2. The bladesharpening device of claim 1, wherein said clamping mechanism isdetachable and includes a means for allowing said clamping mechanism tobe mounted in more than one location on said housing.
 3. The bladesharpening device of claim 2, wherein said clamping mechanism isdetachably mountable perpendicularly to and parallel to said axis ofsaid longitudinal aperture of said grinding member.
 4. The bladesharpening device of claim 1, wherein said clamping mechanism includes acylindrical bore and a cylindrical portion which are companionatelythreaded.
 5. The blade sharpening device of claim 1, wherein saidgrinding member slides horizontally along said shaft by a manual meansof applying a directional force to a pitch adjuster attached to saidgrinding member.
 6. The blade sharpening device of claim 1, wherein saidgrinding member moves horizontally along said shaft by a mechanicalthreaded shank.
 7. The blade sharpening device of claim 1, wherein apitch adjuster is affixed to said grinding member to allow for apreferred angle to be formed between said grinding surface and said edgeof said blade.
 8. The blade sharpening device of claim 1, wherein saidgrinding member includes a circular band of grinding surface thatdefines a formed aperture through which a first cylinder and a secondcylinder, spaced at a predetermined distance so as to secure saidcircular band of grinding surface in a taught position and causing saidaxis of said longitudinal aperture to be centered between said firstcylinder and said second cylinder.
 9. The blade sharpening device ofclaim 8, wherein said means for securing said grinding member to saidshaft member is adapted to allow the detachable securing of said firstcylinder and said second cylinder.
 10. A method of sharpening a blade ofa lawn mower or the like while said blade remains attached to a drivemember of said lawn mower or the like, said method comprising the stepsof: (a) attaching a blade sharpening device to an electrically powered,portable, multi-purpose, multi-use power source producing rotatingmovement, such as a portable power drill, which device includes: agrinding member having a rotatable grinding surface adapted to grind anedge of desired dimensions on a blade; a shaft member, secured to saidgrinding member, having an end thereof adapted for connection with asource of rotational power; securing means for securing said grindingmember to said shaft member; a housing defining a receiving meanscomprising an upper plate and a lower plate between which said blade maybe inserted and a grinding member cavity therein adapted to allow saidgrinding member to rotate about an axis of a longitudinal aperture, whensaid grinding member is secured by said securing means to said shaftmember in a manner such that said grinding member is surrounded by saidhousing; a clamping mechanism, attached to said housing, having a meansfor adjusting said upper plate to compress said blade against said lowerplate to immobilize said blade during an application of said rotatinggrinding surface against said edge of said blade. (b) grasping thehousing of said sharpening device in one hand and said portable powersource in the other; (c) adjusting the location of the housing to allowthe grinding member access to said edge of said blade; (d) positioningsaid grinding member on said blade in a desired location; (e) securingsaid clamping mechanism on said blade in said desired location; (e)initiating transmission of rotational power from said source ofrotational power to said shaft and said grinding member; and (f) movingsaid grinding member along said shaft across said blade while saidgrinding member is in contact with said blade and while the position ofsaid blade sharpening device is controlled said secured clampingmechanism.